This invention relates to a cutting apparatus for a multiple needle cut pile tufting machine, and more particularly to a knife holder apparatus for a cut pile tufting machine.
Conventionally, the knives utilized in multiple-needle cut pile tufting machines for cooperation with looper hooks to form cut pile tufts have been supported in individual knife blocks which includes tracks or guideways for engaging the opposite edges of each knife. Each knife block is provided with a rearward projecting cylindrical stud or rod which is adapted to be rotatably adjustably received in a corresponding hole in a knife bar. This structure permits the knives to be set at the desired tension angles relative to the looper hooks. The stud holes in the knife bars are disposed at angles to the transverse dimension of the knife bar, which are equal to the pitch angle of the knife blades relative to the looper hooks. Each knife is secured in its knife block by a threaded set screw, threadedly received within the knife block for movement toward and away from direct engagement with the edge of each knife.
Other prior art knife holders include knife blocks capable of supporting multiple numbers of knives, such as two, three, four or eight knives each. Furthermore, in some knife blocks, one set screw may be utilized to secure two knife blades, instead of one.
Examples of typical knife holders for multiple needle cut pile tufting machines are shown in the following U.S. Pat. Nos.: 3,277,852, Card, Oct. 11, 1966; 4,003,321, Card, Jan. 18, 1977; and 4,067,270, Short, Jan. 10, 1978.
Because of the continuous vibration of a multiple-needle tufting machine during its operation and the tension between the knives and their corresponding looper hooks, considerable stress is exerted upon the rearward projecting cylindrical studs or rods in the typical knife blocks, causing the knife blocks to rotate, and in turn causing the knives to loose their proper tension angles with their cooperating looper hooks.
Several attempts have been made to provide knife holder apparatus which will rigidly mount the knife blocks relative to the knife bar without depending entirely upon the rearward projecting studs from the knife blocks received within corresponding holes in the knife bar.
In the Cobble U.S. Pat. No. 3,757,709, issued Sept. 11, 1973, although the rearward projecting stud and its cooperating hole are retained, nevertheless, angular channels or guideways are formed in the front face of the knife bar for receiving the back faces of the corresponding knife bars.
T-shaped slots, similar to the vertically disposed angular channels of the above Cobble U.S. Pat. No. 3,757,709 are incorporated in the face of the knife bar of the Card et al patents, U.S. Pat. Nos. 4,608,934, issued Sept. 2, 1986, and 4,669,171, issued June 2, 1987, in order to accommodate an elongated bracket fixed to the knife holder and provided with laterally projecting lugs for slidable reception within the corresponding slots of the knife bar. In the Card et al patents, U.S. Pat. Nos. 4,608,934, and 4,669,171, the rearward projecting stud is eliminated. However, the vertical slidable bracket is retained in position within its corresponding T-slot by detent set screws 41, 141, and 241. In the Card et al patents, the bracket is slidably moved linearly upward along its corresponding slot. As the knives approach their looper hooks, they are flexed by a knife tension tool until the knives engage their corresponding looper hooks. The upward movement of the bracket and knife holder is arrested when the blades are in their operative position cooperating with their corresponding looper hooks, by an arresting pin 38 or arresting set screw 141 or 241. The set screws 41 rely upon their capability of engaging the back surface 33 of the T-slot when tightened, in order to lock the corresponding bracket and its knife holder in its operative position relative to the knife bar, whereas the arresting screws 141 and 241 rely upon their heads bearing against the front surfaces of the brackets adjacent their corresponding slots 140 and 240.
In the co-pending application Ser. No. 145,108, filed, Jan. 19, 1988, of Ray O. V. Magourik, for a "Knife Holder Apparatus for Cut Pile Tufting Machine", each knife block is provided with a depending mast which is slidably mounted within a corresponding slot in the knife bar. A wedge clamp member is adapted to clamp or lock the knife bar carrying a plurality of knives in an operative position relative to the knife bar in which the knives cooperatively engage their corresponding looper hooks. The upper end of each upright slot is enlarged to receive a wedge member and an elongated threaded bolt is inserted upwardly through the knife bar and the slot clamping the wedge member against the mast or staff of the knife block.
However, in both the Card et al patents, U.S. Pat. Nos. 4,608,934, and 4,669,171, and the wedge clamp apparatus of the above pending application of Magourik, the brackets, masts or staffs must first be inserted upward into engagement with their corresponding slots where they are confined in a linear path as the knife blocks are moved upwardly. However, before the knives can be introduced between their corresponding loopers, the knives must be tensioned or twisted, preferably by a tensioning tool, such as that disclosed in FIGS. 13 and 14 of the Card et al U.S. Pat. No. 4,608,934 before the knives can be finally moved upward into their final cooperating positions with their corresponding looper hooks.
Tuftco Corporation, the Assignee of this application, has produced a knife holder module similar to the one disclosed in their prior U.S. Pat. No. 4,445,446, in which an upright key-way is formed in the back of each knife block to register and receive a pin projecting forward from the front face of the knife bar. Moreover, a transverse key or tang projects upward from the transverse tongue for reception within a corresponding key-way in the upper surface of the transverse groove which receives the tongue.